Among contemporary architects, drawing often takes a backseat to computer-aided design software. But the art of drawing is still an essential part of the practice. “To me, drawing is the foundation of architecture,” says Daniel Libeskind in a video produced by Washington University in St. Louis. “There is no substitute.”

Formative drawings from the early careers of Libeskind and several other now-prominent architects will be on display starting in mid-September at Washington University’s Mildred Lane Kemper Art Museum, as part of an exhibition called Drawing Ambience: Alvin Boyarsky and the Architectural Association.

Boyarsky chaired the Architectural Association School of Architecture in London for almost two decades, and his private collection includes architectural drawings from the likes of Rem Koolhaas, Frank Gehry, and Zaha Hadid. Boyarsky saw drawing “not only as a representational medium, but also a form of architectural inquiry unto itself,” as the exhibition curators write.

His collection of drawings, gleaned from the students and practitioners who passed through his school, includes site plans, design proposals, unbuilt works, and theoretical investigations, including an early sketch by Frank Gehry of the Goldwyn-Hollywood Library, and a poster based on the competition drawings for the Office for Metropolitan Architecture’s 1982 master plan for the Parc de la Villette in Paris. Many of the abstract, explorational drawings don’t resemble buildings at all, providing a glimpse into the creativity of the architectural imagination.